The present invention relates to improved solutions for conveying and processing dynamo-electric machine components (e.g., armatures or stators for electric motors, generators, or alternators) in resin application systems. These systems have process principles like those described in U.S. Pat. Nos. 5,401,531 and 5,443,643, which are hereby incorporated by reference herein.
More particularly, a typical resin application system involves impregnating or at least coating the wound coils of a dynamo-electric machine component by dropping liquid resin from a series of dispensers which become aligned with portions of the coil. While this dropping operation occurs, the dynamo-electric machine components rotate under the dispensers so that the resin becomes uniformly distributed on the coils. In traditional systems this operation is accomplished by holding the dynamo-electric machine components with holding devices like those shown in FIG. 4 of U.S. Pat. No. 5,443,643. These holding devices are fixed to a transport chain at a constant distance from each other and have collets for gripping a shaft of the dynamo-electric machine component (in this case an armature). By supporting the ends of the dynamo-electric machine components, these holding devices leave the body portion of the components free from support so that only the components and not the holding devices are coated with resin. A mechanism is also present to produce the rotation which has been described previously.
As an alternative to dropping the resin on the components, it is known to pass the components over a resin bath, which is raised so that a portion of the component is immersed in the resin. The component is then rotated by its holding device so that all portions of its circumference pass through the resin. The bath is lowered after all circumferential portions of the component have received resin.
The above-mentioned holding devices with component rotating capability are certainly satisfactory for manipulating the dynamo-electric machine components with respect to resin dispensers or a resin bath. However, they are expensive to manufacture and their cost becomes an even greater burden when the resin application system needs to have a long chain with a great number of holders to transfer the dynamo-electric machine components to additional equipment like a preheating oven, a curing oven, and/or a cooling plant.
There are other holding devices, such as those shown in FIG. 2 of U.S. Pat. No. 5,401,531, which can be used as satisfactorily as those referred to previously for transporting dynamo-electric machine components through a traditional resin application system. However, these other holders are just as expensive as those described initially.
In view of the foregoing, it is an object of this invention to provide solutions for avoiding the costly result described previously for a resin application system requiring a long chain transport for conveying dynamo-electric machine components through the system.
It is another object of the invention to provide a resin application system which uses two or more sets of dynamo-electric machine component holders, where the more expensive type of holders are used substantially only in the portions of the system where they are required.
Successful application of liquid resin typically requires the workpiece to be heated. For example, heating the workpiece may promote flow of the resin into the spaces or interstices between the wires in the coils of the workpiece. Indeed, it may be desirable to have such complete penetration or impregnation of the coils by the resin that the resin reaches the core of the workpiece via the coils. Optimum heating of the workpiece is desirable to produce the desired degree of resin penetration. Temperatures that are too high should be avoided to prevent premature curing (i.e., hardening) of the resin and/or gas bubble formation in the resin. Temperatures that are too low should also be avoided because the resin may not cure (harden) properly if it does not reach a high enough temperature.
As mentioned above, a preheating oven may be used to preheat the workpieces to the desired temperature for resin application. In order to make sure that all relevant portions of the workpiece are at the desired temperature, it may be necessary for the workpiece to stay in the preheating oven for a relatively long time. At high production rates this may necessitate a large preheating oven and a very long workpiece conveyor (with a large number of workpiece holders) through that oven. It may also be difficult and expensive to precisely regulate temperature in an oven, especially a large oven handling large numbers of workpieces at high production rates.
In view of the foregoing it is still another object of this invention to provide more economical, rapid, precise, and efficient preheating of workpieces for resin application.